Dimensional-Crossover-Driven Mott Insulators in SrVO3 Ultrathin Films

TL;DR

This study demonstrates a transition from metallic to Mott insulating behavior in SrVO3 ultrathin films as their thickness decreases, driven by dimensional crossover effects affecting electron bandwidth and interactions.

Contribution

It provides experimental evidence of a thickness-dependent metal-insulator transition in SrVO3 films caused by dimensional crossover from 3D to 2D, highlighting the role of electron-electron interactions.

Findings

Metallic behavior in thick SrVO3 films with T2 resistivity law.

Observation of a temperature-driven MIT in ultrathin films below 6.5 nm.

MIT attributed to bandwidth reduction and electron-electron interactions.

Abstract

High-quality epitaxial SrVO3 (SVO) thin films of various thicknesses were grown on (001)-oriented LSAT substrates by pulsed electron-beam deposition technique. Thick SVO films (~25 nm) exhibited metallic behavior with the electrical resistivity following the T2 law corresponding to a Fermi liquid system. We observed a temperature driven metal-insulator transition (MIT) in SVO ultrathin films with thicknesses below 6.5 nm, the transition temperature TMIT was found to be at 50 K for the 6.5 nm film, 120 K for the 5.7 nm film and 205 K for the 3 nm film. The emergence of the observed MIT can be attributed to the dimensional crossover from a three-dimensional metal to a two-dimensional Mott insulator, as the resulting reduction in the effective bandwidth W opens a band gap at the Fermi level. The magneto-transport study of the SVO ultrathin films also confirmed the observed MIT is due to the electron-electron interactions other than localization.